In vivo and In vitro interactions between two entomopathogens: the bacterium Serratia marcescens and the nematode Heterorhabditis indica

Abstract

The influence of interaction between Serratia marcescens and Heterorhabditis indica on the penetration, development and proliferation of the latter inside Galleria mellonella larvae was investigated. The preinfection with S. marcescens reduced the penetration of the nematode infective juveniles (IJ) into the infected larvae by 62%. Simultaneous application of the pathogens, however, reduced the IJ penetration only by 21.6%. The development of the juvenile stage into adults was reduced when the pathogens were applied sequentially by 87%, while simultaneous application caused a reduction of 47%. When the IJ were manually injected into larvae preinfected with S. marcescens, their development into adults was reduced by 96%. Finally, a total inhibition of the nematode reproduction was observed inside S. marcescens preinfected larvae. The above findings indicate that the sustainability of this entomopathogenic nematode, when used as a biocontrol agent, or in indoor experimentation, should be carefully evaluated if the soil is heavily contaminated with S. marcescens.